<form id="frmAsignarDocumento">
      <table>
          <tr>
              <td colspan="3">
                  &nbsp;&nbsp;
            </td>
        </tr>
        <tr>
            <td>
               Documentos Sin Asignar
            </td>
            <td>

            </td>
            <td>
                Documentos Asignados
            </td>
        </tr>
        <tr>
            <td>
                <select multiple name="lstDocumentosDisponibles" style="width: 400px; height: 200px">
                </select>
            </td>
            <td>
                <input type="button" name="cmdAsignar" value="Asignar >" style="width: 80px"/> <br/>
                <input type="button" name="cmdRevocar" value="< Revocar" style="width: 80px"/>
            </td>
            <td>
                <select multiple name="lstDocumentosAsignados" style="width: 400px; height: 200px">
                </select>
            </td>
        </tr>
    </table>
</form>